The present invention relates to substrate processing. Specifically, the present invention relates to a device and a method for etching away unwanted portions of film deposited upon a substrate that is less destructive to the substrate and takes substantially less time to perform than prior art etching techniques.
During the fabrication of modern semiconductor devices a backseal process may be employed to protect one side of the substrate from mechanical damage, such as scratching. One benefit of the backseal layer includes providing substrates with a more uniform dopant profile by preventing the dopants from migrating during growth of an epi-layer on an opposing surface. Typically, the backseal process deposits a dielectric film on a side of the substrate positioned opposite to the side upon which patterned features are to be formed.
As is well known, such a backseal layer can be deposited by a chemical vapor deposition (CVD) process. In a conventional thermal CVD process, reactive gases are supplied to the substrate surface where heat-induced chemical reactions take place to form the desired film over the surface of the substrate being processed. In a conventional plasma-enhanced CVD (PECVD) process, a controlled plasma is formed using radio frequency (RF) energy or microwave energy to decompose and/or energize reactive species in reactant gases to produce the desired film.
During deposition of the backseal layer, dielectric material deposits on the peripheral surface of the substrate, positioned between opposed major surfaces of the same. One common method of removing this portion of the backseal layer employs a wet-etch process, such as a bath of hydrofluoric vapor. In addition to being relatively time consuming, the wet-etch process has a tendency to damage the exposed surfaces of the substrate and remove portions of the backseal layer that should remain on the substrate.
Accordingly, improved processes to remove backseal layer from the peripheral surface of a substrate without damaging the substrate or removing the remaining portions of the backseal layer.
A method and a device for removing film from a substrate are provided that take advantage of a remote plasma source to etch away undesired portions of films, such as dielectric films, formed on a substrate. To that end, the method includes remotely forming a plasma with respect to a process chamber. The plasma includes a plurality of reactive radicals from which a flow is created that is directed toward the substrate disposed in the process chamber. The substrate is of the type having opposed major surfaces with a peripheral surface extending therebetween. A film, such as a dielectric film, is disposed on one of the opposed major surfaces, as well as a portion of the peripheral surface. The opposed major surface having the film thereon is shielded from the flow of reactive radicals while the peripheral surface is left exposed. In this fashion, the flow is maintained for a sufficient amount of time to remove film present on the peripheral surface. The device for removing film on a substrate comprises a process chamber having an intake region, a plasma source in electrical communication with an intake region, a pump system in fluid communication with both the plasma source and the process chamber; and a substrate support, having a recess formed therein defining a nadir surface and a side surface. The nadir surface is positioned opposite to an intake region of the recess chamber, and the side surface extends from, and transversely to, the nadir surface toward the intake region, terminating in an opening having an area. The area is substantially coextensive with the intake region.
These and other embodiments of the present invention along with many of its advantages and features are described in more detail in conjunction with the text below and attached figures.